Tablet disruptor device

ABSTRACT

A disruptor device particularly suited for rapidly grinding up pharmaceutical tablets in a liquid and agitating the mixture to dissolve the active ingredients of the tablets in the liquid for subsequent chemical analysis. The device comprises a rotatable shaft extending through a hollow member which is formed at its lower end with a series of circularly arranged spaced teeth. The shaft carries at its lower end a rotor provided with a plurality of teeth which are surrounded by the teeth on the hollow member. Rotation of the rotor draws the tablet and liquid upward into the rotor and propels the mixture radially outward through the teeth in the hollow member whereby the tablet will be severed and broken into pieces by the shearing action between the two sets of teeth. Some of the teeth on the outer hollow member are shorter than the other teeth thereon so as to provide entrance openings for large particles to enter the head of the device. An inverted conical shaped deflector is provided on the bottom of the rotor to eliminate stagnant eddy currents within the rotor.

United States Patent 1 [11 1 3,724,75 Rohrbaugh et al. 1 Apr. 3, 1973[54] TABLET DISRUPTOR DEVICE [57] ABSTRACT [75] Inventors: Donald G.Rohrbaugh, Santa Ana; A disruptor device particularly suited for rapidlyEverett Petersen, Jr" Glendon, grinding up pharmaceutical tablets in aliquid and both of Calif. agitating the mixture to dissolve the activeingredients of the tablets in the liquid for subsequent chemical [73]Asslgnee F Instruments Funar' analysis. The device comprises a rotatableshaft ex- Cd tending through a hollow member which is formed at [22]Filed: Sept. 3, 1971 its lower end with a series of circularly arrangedspaced teeth. The shaft carries at its lower end a rotor PP NOJ 177,555provided with a plurality of teeth which are surrounded by the teeth onthe hollow member. Rotation 52 us. Cl ..24l/46.06 241/188 R 241/258 0fthe draws the tablet and liquid upward into 259/96 the rotor and propelsthe mixture radially outward [51] Int Cl nozc 18/10 1302c 13/18 throughthe teeth in the hollow member whereby the [58] Fieid 46 06 i 17 46 08tablet will be severed and broken into pieces by the 241/DIG 6 shearingaction between the two sets of teeth. Some of l A 259795 108 the teethon the outer hollow member are shorter than the other teeth thereon soas to provide entrance openings for large particles to enter the head ofthe [56] References Cited device. An inverted conical shaped deflectoris pro- UNITED STATES PATENTS vided on the bottorn of the rotor toeliminate stagnant I eddy currents within the rotor. 2,324,018 7/1943Petersen ..24l/188 A UX 2,903,197 9/1959 Willems.... ..24l/46.06 X2,789,800 4/1957 Willems ..259/1O8 6 Claims, 5 Drawing Figures PrimaryExaminer-Donald'G. Kelly Attorney-Thomas L. Peterson et al.

I l I I 6 l i 9 a I y 1 1 I li i I flan FLOW TABLET DISRUPTOR DEVICEBACKGROUND OF THE INVENTION 'in recent years to develop automatedchemical analyzers, particularly in the field of clinical chemistry.More recently a need has arisen for automated chemical analyzers capableof determining quantitatively the active ingredients in pharmaceuticaltablets or capsules in order that close quality control may bemaintained on the manufacture of these products. An initial fimctionwhich must be performed by such an analyzer is the severing and breakingup of the tablets into small pieces and the dissolvingof the activeingredients of the According to the principal aspect of the presentinvention, there is provided a device similar to the beforementionedWillems Polytron in which some of the teeth on the outer shaft arelonger than the other teeth thereon so as to provide enlarged entranceopenings for solid particles to enter into the head of the device fordisruption and mixing with the liquid. Also, an inverted cone-shapedelement is provided on the bottom of the 0 rotor to establish astreamlined liquid flow pattern tablets in a suitable liquid. Thisfunction must be per- I machines have been employed for dispersing anddissolving tablets in solvents for chemical analysis. However, suchdevices are relatively slow and inefficient in performing this function.

We have attempted to utilize a commercially available device called theWillems Polytron for grinding up and dissolving pharmaceutical tabletsin liquid but have found the device not to be sufficiently efficient andrapid to be practical for use in a high speed automated chemicalanalyzer. Such commercial device is similar to that disclosed in US.Pat. No. 2,789,800 to Willems. The commercial device includes a hollowouter shaft and a central shaft extending axially through the outershaft. The outer shaft is formed at its lower end with a plurality ofcircularly arranged, spaced'teeth. The inner shaft carries at its lowerend a rotor comprising a laterally extending arm having a pair ofdownwardly extending teeth at opposite ends thereof which are in closeradial proximity to the teeth on the outer shaft. Upon rotation of theinner shaft, a mixture into which the head of the device is immersedwill be drawn upwardly into the rotor and radially outward between therelatively rotating teeth whereby solid particles in the mixture will besubjected to a shearing action between the teeth. The mixture will thusbe continuously recirculated through the head of the device, effecting adisruption of the solid particles and dissolution of the same into theliquid. For reasons which will be discussed later herein, the WillemsPolytron is not fully effective for rapid and efficient grinding up anddispersing of pharmaceutical tablets or capsules of conventional size.

SUMMARY OF THE INVENTION through the head of the device to eliminate anystagnant eddy currents within the rotor.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevational view ofthe prior art Willems Polytron with the head thereof shown positioned ina container of solution;

FIG. 2 is a partial longitudinal sectional view through the head of thedevice illustrated in FIG. 1;

FIG. 3 is a longitudinal partial sectional view through the head of atablet disruptor device constructed in accordance with the presentinvention;

FIG. 4 is a side elevational view of the lower end of the outer shaftillustrated in FIG. 3; and

FIG. 5 is a horizontal sectional view taken along line 55 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing indetail, FIGS. 1 and 2 illustrate the prior art Willems Polytron device,

generally designated 8, with its lower end or head 9 positioned in acontainer 10 holding a solvent 11. The device 8 includes an electricmotor 12 which drives a central shaft 14 mounted within an outer hollowshaft 16. The outer shaft 16 is suitably secured to the housing of themotor 12 to form a stator. The lower end of the shaft 16 is formed witha series of circularly arranged spaced teeth 18 concentric with thelongitudinal axis of the shaft 14.

A rotor 20 is fixedly mounted on the end of the shaft 14. The rotorincludes a laterally extending arm 22 symmetrically mounted with respectto the axis of rotation of shaft 14. A pair of downwardly extendingteeth 24 are formed at opposite ends of the arm providing therebetween adownwardly facing open suction space 25. The outer surfaces of the teeth24 lie in close radial proximity to the inner surfaces of the teeth 18on the outer shaft 16. As can best be seen in FIG. 2, the lower ends 26of the teeth 24 on the rotor are recessed behind or above the lower ends28 of the teeth 18 on the outer shaft 16. I

In operation of the prior art device 8, the shaft 14 and thus the rotor20 is rotated ata high speed by the motor 12. Rotation of the rotordraws liquid up into the suction space 25 in the rotor and outwardlybetween the teeth on the rotor and stator whereby solid particles in theliquid are severed and broken into pieces by the shearing action betweenthe two sets of teeth. However, our tests of the prior art device 8 ingrinding up and dissolving pharmaceutical tablets has revealed twodistinct problems. One, the normal size pharmaceutical tablet,designated 32, often adheres by suction to the end of the head of thedevice 8, as seenin FIG. 2, so that the tablet is not disintegrated.Also, once a tablet is partially disintegrated particles thereof, suchas indicated by numeral 34, become trapped by the eddy currents,indicated by arrows 35, in the suction space within the rotor and willnot recirculate for further shearing action by the teeth of the device.Thus, disrup tion and dissolving in liquid of pharmaceutical tablets bythe device 8 is generally unreliable and, at best, takes at leastseconds to 2 minutes to accomplish.

Reference is now made to FIGS. 3-5 which illustrate the head of a tabletdisruptor device constructed in ac cordance with the present invention.In this device the basic structure is as previously described inconnection with the device 8 and like numbers primed are used toindicate like or corresponding parts. The stator or outer shaft 16' ofthe device 8' of the present invention differs primarily from the stator16 in the device 8 in that every second tooth 18a is shorter in theaxial direction than the next adjacent tooth l8b so that the longerteeth 18 are positioned alternately with respect to the shorter teeth18a about the stator 16. Preferably, as shown, the shorter teeth l8'aare about one half as long as the longer teeth 18'b. Thus, there areprovided between the lower ends of the longer teeth l8b enlargedentrance spaces for the capsule 32 allowing the capsule to becomeeffectively subjected to the grinding action of the teeth on the rotorand stator without adhering to the end of the device by suction.

The rotor 20 in the device 8 of the present invention is essentiallyidentical to the rotor 20 discussed previously except that the rotor 20'is formed with an inverted cone-shaped deflector 36 the base of which isintegral with the arm 22 of the rotor and the tip 38 extends into thesuction space 25 but terminates short of the lower ends 26' of the teeth24. As will be seen in FIG. 3, the teeth 24' on the rotor 20 are spaceda sufficient distance from the surface of the conical portion 36 of therotor so as to provide ample space for the free flow of liquid andparticles up into the suction space 25 whereby such material will besubjected to the shearing action between the teeth on the rotor andstator and propelled outwardly in a pattern as shown by the arrows inFIG. 3. The conical section 36 of the rotor 20' establishes astreamlined liquid flow pattern which eliminates the eddy currents whichexist in the device 8 illustrated in FIGS. 1 and 2, thus ensuring thatall particles will be rapidly and efficiently circulated through thehead of the device 8.

It is further noted that the lower ends 26' of the teeth 24' on therotor are essentially coplanar with the lower ends of the longer teethl8b on the stator, thus max imizing the amount of shearing actionbetween the teeth at the end of the head 9.

A disruptor device as illustrated in FIGS. 3-5 has been constructed inwhich the outer diameter of the stator was 0.875 inch, the innerdiameter of the stator was 0.625 inch, and the teeth on the stator werespaced apart 0.094 inch. The longer teeth l8b were 0.500 inch long andthe ends of the shorter teeth 18a were recessed behind the ends of thelonger teeth 0.25 inch. The outer diameter of the rotor 20' was 0.610inch and the width of the teeth 24 on the rotor was 0.15 inch. It isunderstood of course that these dimensions are given by way ofillustration only and not by limitation. The device having a head of theforegoing dimensions was tested for efiiciency and reliability using thesame type of tablet and solvent as was the beforementioned WillemsPolytron and was found capable of completely and reliably disrupting anddissolving a tablet within the solvent within 5 seconds, as comparedwith the Willems Polytron which required at best 30 seconds to 2 minutesand was unreliable.

The effectiveness of the tablet disruptor device of the presentinvention is believed due to the optimizing of the head configuration ina manner to balance the conflicting requirements of providing maximumshearing surfaces between the teeth for rapidly grinding the solidparticles drawn into the head while providing sufficiently large spacesbetween the teeth to permit large particles to enter the suction'space.The use of altemating short and long teeth on the stator achieves thisresult. Needless to say, depending upon the size of the tablets or solidmaterials which are to be ground up by the device 8 of the presentinvention, fewer or larger number of teeth may be provided on thestator. For example, for smaller particles to be ground up, a largernumber of teeth may be provided and may be spaced more closely togetherand the opposite would be the case for larger particles. In addition,the rotor may carry more than two teeth, particularly where smallerparticles are to be ground up by the device.

Although several embodiments of the invention have been disclosed hereinfor purposes of illustration, it will be understood that various changescan be made in the form, details, arrangements and proportions of thevarious parts in such embodiments without departing from the spirit andscope of the invention as defined by the appended claims.

What is claimed is:

1. A device for disrupting tablets or other solid materials in a liquidcomprising:

a hollow member;

a rotatable shaft extending axially through said member;

means for rotating said shaft;

a rotor fixed to one end of said shaft;

a series of circularly arranged spaced teeth secured to one end of saidhollow member and concentric with the axis of rotation of said shaft;

said rotor including a plurality of teeth extending beyond said one endof said shaft, said rotor teeth being surrounded by said series of teethand positioned in sufficiently close radial proximity thereto so that ashearing action will be produced by said teeth on solid materials drawninto engagement with said teeth by rotation of said rotor; and

at least some of the teeth of said series being longer in the axialdirection than the other of said teeth.

2. A device as set forth in claim 1 wherein:

said rotor includes a laterally extending arm mounted on said one end ofsaid shaft symmetrically with respect to said axis, said rotor teethbeing remote from the center of said am to provide a central suctionspace.

' 3. A device as set forth in claim 2 wherein:

said arm is formed with an inverted conical center portion concentricwith said axis and extending into said suction space.

4. A device as set forth in claim 1 wherein:

the longer teeth of said series and said rotor teeth terminate insubstantially the same radial plane.

5. A device as set forth in claim 1 wherein:

6 the longer teeth of said series are positioned alvide a centralsuction space; and

telately wlth respect to the other of sand teeth of said rotor is formedwith an inverted conical center said series. 6. A device as set forth inclaim 1 wherein: $2 2? zz f zl z x sand was and extendmg there areprovided two diametrically opposed rotor 5 p teeth spaced from thecenter of said rotor to pro-

1. A device for disrupting tablets or other solid materials in a liquidcomprising: a hollow member; a rotatable shaft extending axially throughsaid member; means for rotating said shaft; a rotor fixed to one end ofsaid shaft; a series of circularly arranged spaced teeth secured to oneend of said hollow member and concentric with the axis of rotation ofsaid shaft; said rotor including a plurality of teeth extending beyondsaid one end of said shaft, said rotor teeth being surrounded by saidseries of teeth and positioned in sufficiently close radial proximitythereto so that a shearing action will be produced by said teeth onsolid materials drawn into engagement with said teeth by rotation ofsaid rotor; and at least some of the teeth of said series being longerin the axial direction than the other of said teeth.
 2. A device as setforth in claim 1 wherein: said rotor includes a laterally extending armmounted on said one end of said shaft symmetrically with respect to saidaxis, said rotor teeth being remote from the center of said arm toprovide a central suction space.
 3. A device as set forth in claim 2wherein: said arm is formed with an inverted conical center portionconcentric with said axis and extending into said suction space.
 4. Adevice as set forth in claim 1 wherein: the longer teeth of said seriesand said rotor teeth terminate in substantially the same radial plane.5. A device as set forth in claim 1 wherein: the longer teeth of saidseries are positioned alternately with respect to the other of saidteeth of said series.
 6. A device as set forth in claim 1 wherein: thereare provided two diametrically opposed rotor teeth spaced from thecenter of said rotor to provide a central suction space; and said rotoris formed with an inverted conical center portion concentric with saidaxis and extending into said suction space.